"Why did we decide to partner with Google?" Fadell wrote in a blog post. "Google will help us fully realize our vision of the conscious home and allow us to change the world faster than we ever could if we continued to go it alone. We've had great momentum, but this is a rocket ship. Google has the business resources, global scale, and platform reach to accelerate Nest growth across hardware, software, and services for the home globally."

Google had apparently already signaled that it was interested in being involved in the smart-home space. There had been rumors that the search giant was already working on its own smart thermostat. And in his blog post, Fadell said that "Google has been in the mix in some way or another for about three years of our almost four-year history. In fact, my first meeting with Google as a Nester was before we'd launched."

Some might have thought, though, that Apple would be a good suitor for Nest, especially given that Fadell and co-founder Matt Rogers both had deep Apple backgrounds. But Fadell wrote today that Google founder Sergey Brin "instantly got what we were doing and so did the rest of the Google team" when they got a Nest demo at the 2011 TED conference.

In a press release, Google CEO Larry Page said that, "They're already delivering amazing products you can buy right now -- thermostats that save energy and smoke/[carbon monoxide] alarms that can help keep your family safe. We are excited to bring great experiences to more homes in more countries and fulfill their dreams!"

For Nest, having substantial new resources should make it much easier for it to hold off legacy competitors like Honeywell. As well, Google's deep pockets could help Nest in ongoing litigation with Honeywell.

In a blog post Monday, Rogers addressed whether Nest customers' data will be shared with Google: "Our privacy policy clearly limits the use of customer information to providing and improving Nest's products and services. We've always taken privacy seriously and this will not change." Rogers also added that Nest will continue to support iOS devices.

The acquisition, pending regulatory approval, is expected to close in a couple of months.